Not Applicable.
Not Applicable.
This invention relates to a chair having a J-back support mechanism between the back and the seat of the chair and, more particularly, to a method of optimizing the configuration of the J-back for the chair.
Chairs having seats and backs that are separate, but connected, are well known in the art. Some of these chairs have what is known as a xe2x80x9cJ-backxe2x80x9d that is used to connect the seat to the back. The configuration of the J-back thus determines the location of the back relative to the seat. Therefore, the geometry of the J-back is of paramount importance in determining the overall comfort of a person sitting within the chair. These J-backs are used in chairs where the back moves in direct proportion to the seat (non-synchronized tilt mechanisms) and where the back is allowed to move or tilt at a different rate from the seat (synchronized tilt mechanisms).
In the design of chairs, and particularly chairs with synchronized tilt mechanisms, it is desirable to lessen or eliminate two particular conditions. The first condition is known as xe2x80x9cbridging.xe2x80x9d Bridging occurs when the backrest rotates downwardly and rearwardly from the seat to an extent that reduces lumbar support upon tilting, which can reduce the comfort of the user. The second condition is known as xe2x80x9cshirt-pull.xe2x80x9d Shirt-pull occurs as the backrest rotates upwardly and rearwardly from the seat during tilting. In other words, shirt-pull occurs during the normal recline and return of the backrest. As this motion occurs, the shirt of the person sitting in the chair has a tendency to untuck during tilting, which is undesirable.
Therefore, in designing chairs, it is necessary to consider these two conditions and to attempt to minimize the occurrence or severity of the two conditions as much as possible. Traditionally, this design effort involved constructing a chair having a given tilt mechanism, seat, back and J-back. A person of average build would then sit in the chair and evaluate the overall comfort, bridging and shirt-pull that the user experienced. The configuration of the J-back could then be altered based upon the user""s input of the conditions experienced, and the process would continue until the user experienced an acceptable level of comfort when using the chair. Such a design process, however, is both subjective and time-consuming.
It is known within the art to utilize a J-back calibration device to reduce the time required between iterations of the design process. The J-back calibration device allows the chair designers to simulate a J-back and quickly change the configuration of the J-back shape between iterations. In other words, the J-back calibration device assists the designers by allowing them to change the shape and configuration of the J-back during the design process. The J-back calibration device thus allows the relationship between the chair seat and the chair back to be changed, both in distance and in angles. As the J-back calibration device is changed, the chair designers have a person sit in the chair, as changed, to evaluate the comfort of the chair, as well as the shirt-pull and bridging experienced. Once an acceptable comfort level has been achieved, the chair designers use the shape and dimensions of the J-back calibration device from the last iteration to design the J-back for the chair. While the use of the J-back calibration device has decreased the time needed in the design process, it does nothing to address the subjectivity involved in the design process. Moreover, the use of the J-back calibration device relies upon the chair designers to know which distances and angles to change on the J-back calibration device to increase the comfort of the user and to reduce shirt-pull and bridging.
Another device that is known within the art is referred to as a xe2x80x9cchair measurement devicexe2x80x9d or xe2x80x9cCMD.xe2x80x9d The CMD and its method of operation are described in U.S. Pat. No. 5,564,195 issued to Kokot et al., and assigned to The Business and Institutional Furniture Manufacturers Association. The CMD is useful in measuring the amount of shirt-pull and bridging that occur in a given chair configuration. Thus, the CMD can be used to provide more objective information about two of the major design considerations. The CMD does not, however, reduce the design time of the chair, and does not offer any guidance to the chair designers as to how to reduce the shirt-pull and bridging that may be occurring.
Accordingly, there exists a need for a method in the design of J-backs for use on chairs which overcomes the above drawbacks and deficiencies. More specifically, a method is needed that reduces the design time required for a particular J-back associated with a given chair seat and back, that reduces the subjectivity of the design process and that guides chair designers in the proper configuration of the J-back.
It is an object of the present invention to provide a method for optimizing the configuration of a J-back for a chair that reduces the time needed to design a J-back resulting in a minimum amount of shirt-pull and bridging.
It is a further object of this invention to provide a method for optimizing the configuration of a J-back for a chair by reducing the subjectivity involved in the design process.
According to the present invention, the foregoing and other objects are obtained by a method that combines the measurements obtained from a CMD, the settings and adjustments available with a J-back calibration, and the analysis that can be provided with a Design of Experiments (DOE) software or other similar statistical analysis and plotting software.
Additional objects, advantages, and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.